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Block 2 - Theme Three
heart junk
53
Biology
Graduate
11/03/2008

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Term
What is the difference between myocardial infarction and myocardial ischemia?
Definition
Ischemia results from when O2 supply does not meet demand, whereas MI is necrosis caused by prolonged ischemia; therefore, you can have ischemia and not necessarily infarction.
Term
The inadequate coronary flow that causes ischemia/infarction is due to which- increased demand (exercise) or reduced supply of blood (occluded artery)?
Definition
Both, conversely the way to manage ischemia is to reduce demand or increase supply
Term
In the sequence of functional failure during MI, which of these two groups occurs first: 1- impaired rate of relaxation, impaired force generation, rapid K leak and Na gain, or 2- onset of contracture, onset of Na-K pump failure?
Definition
Group 1 occurs immediately, group 2 occurs after 15 minutes.
Term
What are the two metabolic responses to ischemia?
Definition
Huge increase in use of stored glycogen (anaerobic glycolysis), and sacrifice of creatine phosphate
Term
What are the 2 major causes of impaired heart muscle relaxation in MI, that is both related to reduced ATP and increased ADP concentration?
Definition
Reduced Ca resequestration by the SR, and increased ADP/ATP inhibits cross-bridge release
Term
True or False: During ischemia, LVEDV will be greater and the LVEDP will be lower.
Definition
False, LVEDV will be smaller due to reduced ability to relax and therefore LVEDP will be higher
Term
Which of the following happens early in ischemia to impair active force development - the garden hose effect, increased H+ and Pi inhibiting Ca binding to troponin, or increased ATP-sensitive K current which shortens systole.
Definition
All of them happen
Term
Since you decreased contractility during ischemia, what happens to stroke volume, LVEDP, LVEDV?
Definition
SV goes down, LVEDV increases because of leftover blood not ejected, LVEDP increases due to larger volume of blood and less relaxation
Term
True or False: the result of decreased ATP and increased ADP in the cell on the flux of K+ results in the opening of ATP sensitive K+ channels and opening of non-selective cation channels allowing Na+ to flow in the cell.
Definition
True, this shortens the action potential duration, and depolarizes the membrane and may cause arrythmias because Na channels become inactivated
Term
What is the result of intracellular Na rising in the cell during ischemia?
Definition
Membrane depolarization and an increase in intracellular Ca due to the NHE and Na/Ca exchangers.
Term
True or False: the fall in Ca levels in the cell results in activation of proteases, destruction of enzymes and cytoskeletal elements, intake of Ca in mitochondria resulting in functional arrest, depletion of high energy phosphates due to energy dependent Ca pump in mitochondria.
Definition
False, the rise Ca levels results in these things.
Term
When does necrosis occur in ischemia?
Definition
20-30 minutes after onset, 3-6 hours after completed infarct
Term
Where in the vessel wall does necrosis start and end in infarction?
Definition
It starts in the subendocardium and moves to the epicardium
Term
Which of these are the major clinical findings of MI: angina, dyspnea, diaphoresis, nausea, bowel movements.
Definition
All except bowel movements.
Term
Which 3 enzymes can you check for in the blood due to MI (tissue necrosis)?
Definition
Troponin I and T, Creatine Kinase, Myoglobin
Term
What will you see in an ECG that reveals an MI?
Definition
ST interval elevation, for ischemia there is ST interval dperession
Term
In the management of ischemia how do you increase supply and reduce demand?
Definition
Increase supply by angioplasty, platelet inhibitors like aspirin/clopidigrel, thrombolytics, and bypass surgery; reduce MvO2 demand with beta blockers, reduce preload with nitrates (venodilators), ACE inhibitors like captopril due reduce afterload (vasodilation).
Term
What is the result of ischemia on coronary perfusion pressure?
Definition
The reduced diastolyic aortic pressure (less stroke volume) and increased diastolyic ventricular pressure (heart can’t relax) causes a reduction in perfusion pressure.
Term
What are the elements and steps of the Users Guide Method?
Definition
Begin with a clinical scenario (either PBL or real patient), Search online for published info, Select one or more studies, Read and critically appraise the studies (PICO, validity, results, application)
Term
In regards to UGM, what is PICO?
Definition
The criteria with which to frame searchable clinical questions - Patients, Intervention, Comparison Group, Outcome
Term
What are the equations for - relative risk, relative risk reduction, absolute risk reduction, and number needed to treat?
Definition
RR - treatment risk/control risk; RRR - control - treatment/control; ARR - control-treatment; NNT - 1/ARR
Term
What type of study is the gold standard for judging the impact of therapies?
Definition
Clinical trials, which should be performed when there is significant observational data but have important unanswered questions.
Term
In regards to studying therapies, what is a cointervention?
Definition
Interventions other than treatment under study that may be differentially applied to experimental and control groups, potentially biasing study
Term
What is irreversible perfusion injury?
Definition
A form of necrosis that does not occur until reperfusion of ischemic tissues, the longer it takes to reperfuse, the more likely that injury will occur
Term
Why does reperfusion of ischemic tissue cause damage, shouldn’t blood flow restore function?
Definition
Blood flow causes oxidative burst generating free radicals primarily from leukocytes but also endothelium and myocytes
Term
In reperfused ischemic tissues what happens after free radicals arrest metabolism?
Definition
They inhibit Na/K pump raising intracellular Na, stimulate Na/Ca exchanger (1Ca for 3 Na), leads to intracellular Ca overload, havoc ensues
Term
True or False: free radicals cause direct lipid peroxidation disrupting sarcolemma and also induce apoptosis (along with cytokines, neurotrans, Ca)
Definition
true
Term
In reperfused myocardium, what is stunning?
Definition
Reversible reperfusion injury, a key feature of which is to overcome contractility deficits with ionotropes.
Term
In reperfusion stunning, what is the relationship between Ca and force production?
Definition
Ca overload activates proteases, damaging myofilaments so that they are unable to respond normally to activation by Ca, decreases maximum force production
Term
What 2 things does an ACE inhibitor do?
Definition
Dilates vasculature and improves myofilament Ca response (good to treat stunning)
Term
What is Hibernating myocardium?
Definition
Chronically ischemic but not necrotic tissue with impaired contractility and relaxation, normal metabolism, akinetic or hypokinetic
Term
True or False: the best treatment for hibernating myocardium is ionotropic agents to improve function as opposed to revascularization.
Definition
False, ionotropes may provoke ischemia, revascularization is curative through angioplasty
Term
True or False: maladaptive remodeling, following myocardial necrosis, leads to ventricular reduction, decreased wall tension, and increasing function.
Definition
False, ventricular enlargement, increased wall tension, and deteriorating function.
Term
What 3 things do you use to prevent maladaptive remodeling?
Definition
B-blockers, ACE inhibitors, aldosterone antagonists
Term
Preconditioning of the heart is from repetitive bouts of brief ischemia, what is the benefit of this?
Definition
It confers protection against a more prolonged episode of ischemia and reperfusion, due to effectors like ATP-sensitive K+ channel
Term
In reperfusion injury, why is it advisable to only use ionotropes when absolutely necessary to prevent hypotension?
Definition
These agents increase MvO2, generating free radicals and giving less time for repair
Term
What is aortic stenosis and what is the ventricular response?
Definition
Degenerative and calcification change in valve reducing aortic valve area; the ventricle responds by concentric left ventriclular hypertrophy to normalize wall tension
Term
What is the symptomatic triad of aortic stenosis?
Definition
Dyspnea(diastolyic dysfunction increases fillng pressure backing up fluid in chest), angina (pain due to MvO2 supply/demand mismatch due to hypertrophy), vasodepressor syncope (too much dilation)
Term
In aortic stenosis, how does the modified myocardial perfusion gradient change heart blood supply?
Definition
The hypertrophied heart compresses coronaries resulting in decreased perfusion, in combo with decreased diastolyic aortic pressure reduces the hearts blood supply.
Term
What is the leading cause of mitral stenosis?
Definition
Rheumatic heart disease
Term
What is the result of mitral stenosis in the short term and long term?
Definition
The obstructed blood flow causes an enlargement in the left atrium due to increased filling pressure; overtime, this often leads to development of atrial fibrillation (depriving patient extra 25% they would have in normal rhythym) and fixed pulmonary hypertension and right ventricular failure.
Term
During development, during which weeks does the cardiovascular system begin to develop and which week does it start to beat?
Definition
3rd, 4th
Term
During cardiovascular development, during which weeks does septation of the heart into four chambers happen?
Definition
4-7
Term
True or False: congenital heart defect are uncommon at <1% of births.
Definition
False, they are considered common, particularly cardiac/ventricular septal defects
Term
Failure of appropriate circulatory changes to occur at birth is the cause of two of the most common congenital anomalies, which are?
Definition
Patent oval foramen and patent ductus arteriosus
Term
During cardiovascular development, what is coarctation?
Definition
Descending aorta pinches off and fuses with patent ductus arteriosus or blood is shunted to collateral arteries
Term
What are the 5 T’s of cyanotic heart disease?
Definition
Truncus arteriosus (no aortic pulmonary septation), transposition of great arteries, tricuspid atresia, teratology of fallot, total anomalous pulmonary venous return
Term
In the teratology of Fallot, what does the acronym PROV stand for?
Definition
Pulmonary artery stenosis, right ventricular hypertrophy, over-riding aorta, ventricular septal defect
Term
What is aortic regurgitation and what are its symptoms?
Definition
It is the backflow of blood across the valve during diastole due to either intrinsic valve abnormalities or aortic root abnormalities; this problem presents with dyspnea and angina, with mid-diastolic crescendo murmur.
Term
What is the acute and chronic result of aortic regurgitation?
Definition
The acute response is mild increase in EF, increased LVEDP then pulmonary pressures and dyspnea; the chronic response is elevated EF, normalized LVEDP and eccentric hypertrophy of the heart, although there is a decompensation point where LVEDP rises, EF drops, and symptoms develop.
Term
What is the first abnormality that occurs in myocardial ischemia?
Definition
Abnormal relaxation
Term
What does an elevated or depressed ST segment indicate?
Definition
MI or Coronary artery disease
Term
What is the difference between S3 and S4 heart sounds?
Definition
S3 occurs after S2 and indicates blood flowing against a non-compliant ventricle in mid-diastole, S4 occurs before S1 at the end of diastole for the same reason
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